1. Field of the Invention
The present invention relates to a novel human B-cell line and more specifically to a human B-cell line for the production of a novel monoclonal antibody to an antigen of human gastric cancer, to the antibody so produced and to the antigen.
2. Description of the Prior Art
The capacity of the human body to produce immunoglobulins has found applications in medicine and industry. The ability of the human auto-antibody production system to distinguish cancer-related antigens from almost all of the normal cells in the human body has found a wide range of applications in the detection and therapy of cancers. In diagnostic applications, radio-isotope-coupled immunoglobulins can be used to identify the location of cancer in a patient. On the other hand, in therapeutic applications immunoglobulins can be used for passive immunization or site-directed therapy against cancer. Major stumbling blocks in the wide use of human immunoglobulin therapy have been a limited probability of selecting B-cell clones and instability of the cell cultures which can produce monoclonal antibodies. The cancer-related antigens defined by human auto-antibodies can also be employed in the active immunotherapy of cancer and as therapeutic markers of cancer.
The discovery by Milstein and Kohler of mouse hybridomas capable of secreting specific monoclonal antibodies against predefined antigens ushered a new era in the field of experimental immunology. The clonal selection and immortality of such hybridoma cell lines assure the monoclonality, monospecificity and permanent availability of their antibodies. However, in human clinical applications the use of such mouse antibodies is clearly limited by the fact that they are foreign proteins and would act as antigens.
A popular method for obtaining a human monoclonal antibody is the transformation of B-cells by treating the cells with culture medium from a marmoset cell line which contains Epstein-Barr virus (hereinafter "EBV"). In clinial applications, the antibody obtained by this method is inevitably contaminated with other viruses from the marmoset cell line.
Another method for the transformation of B-cells is disclosed in detail in U.S. Pat. No. 4,464,465 which employs a human B-cell line as the source of EBV.
A. Ochiai et al. [Proceedings of the Japanese Cancer Association, The 44th Annual Meeting October 1985 (TOKYO) pp132] disclosed a new human gastric cancer-related antigen having a molecular weight of about 46 kilodaltons which exists in tissues of gastric cancer, colon cancer, lung cancer and so on, and which further exists in neutrophil leukocytes which are one type of leukocytes or macrophages.